Re: So let me get this right: (Was: NFNF vs 1NF ...)

DBMS_Plumber wrote:
>
> > But bag data model makes rutime far less efficient.
>
> Evidence? (Besides a handful of example queries where this is
> obviously true, usually characterized by the way that the answer
> includes a Cartesian product of keys...)
>
> What you've stated is the opposite of what early systems builders
> concluded.

Yes, and even earlier system builders concluded that the RDBMS would never fly because it did not let the programmer "navigate".

There is no motivation to find out because we are locked into SQL now.

> And given that that the contents of an XML document are
> 'strictly ordered', and therefore posess set properties (implicitly,
> every node in an XML document is preceeded by an implied value which
> distinguishes that node from all others) we're about to find out just
> how efficient a set algebra can be.
>

Do values of sets have implicit order? I don't think so. You are placing a heavy burden on the system if it has to maintain order so as to retain identity.

>
> (Note: I ain't sayin' either way. I'm just sayin' the case is far
from
> clear. This is an empirical question, not a theoretic one.)
>

Fair enough, but you have to admit that there has not been that much work done on investigating this. There is no motivation, because SQL doesn't need it.

>
> Any my point is that you appear to believe that Date, Darwen & Pascal
> have a unique ability to "correctly interpret".
>

Don't worry, nobody's paying attention. They are all too busy trying to figure out new ways to index XML-databases.

regards,
Lauri Pietarinen Received on Fri Feb 11 2005 - 00:46:13 CET